SiC Sinterable Powder for Dense Pressureless Slip Casting
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Solution Overview
Problem
Current methods for manufacturing dense silicon carbide (SiC) bodies through pressureless sintering using slip casting fail to achieve high density, especially for complex shapes or large dimensions, due to limitations in powder properties and processing techniques.
Innovation Solution
A sinterable powder comprising co-milled SiC and boron compounds with a carbon-containing source, where the average particle size is between 0.5 to 2.0 micrometers, and the carbon source is water-insoluble, allowing for high-density SiC-based sintered bodies to be produced via pressureless sintering without initial high-pressure molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional slip casting methods are used with submicronic SiC powders, then the process can be implemented for shaping, but the resulting sintered body exhibits low density even at high firing temperatures
Solution Approach 1:
The patent changes the particle size parameter from submicronic to 0.5-2.0 micrometers, which fundamentally alters the sintering behavior and enables high density achievement through pressureless sintering while maintaining slip casting processability
Solution Approach 2:
The patent creates a composite powder system combining SiC with specific boron compounds (B4C, B2O3) and carbon sources, where the synergistic interaction between components enables both slip casting processability and high density sintering outcomes
2Manufacturing precision
If intensive grinding is used to reduce SiC particle size to submicronic levels, then the required fineness is achieved, but additional dry milling steps are required which are sources of contamination and cost
Solution Approach 1:
The patent performs preliminary wet grinding to achieve the target particle size range of 0.5-2.0 micrometers before slip casting, eliminating the need for subsequent dry milling steps and preventing contamination from additional processing
Solution Approach 2:
The patent uses water as an intermediary medium during grinding and slip casting, enabling particle size reduction and shaping in a single wet process rather than requiring separate dry milling steps that would contaminate the material
3Ease of manufacture
If organic solvents and additives are used for slip casting, then shaping can be achieved, but environment issues arise and the process becomes difficult to implement
Solution Approach 1:
The patent replaces persistent organic solvents with water, a benign and easily removable medium, eliminating environmental contamination issues while maintaining slip casting shaping capability
Solution Approach 2:
The patent uses water as an inert and environmentally friendly medium for slip casting, creating a clean processing environment that eliminates the harmful effects associated with organic solvents
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves a relative density of over 95% of the theoretical density, enabling the production of dense SiC-based products with complex shapes or large dimensions, surpassing previous limitations in slip casting and sintering processes.
Implementation Method 1
pressureless sintering process
Data Source
AI summary
A SiC based sinterable powder mixture comprising, by dried weight of said powder: a) a mineral content comprising—silicon carbide (SiC) particles, —mineral boron compound particles, the powder comprising at least 50% by weight of SiC and the total mineral content of the powder being at least 90% by weight, b) at least a water insoluble carbon-containing source, in particular a carbon containing resin, the powder comprising at least 1% by weight, and preferably less than 10% by weight, of said water insoluble carbon-containing source, wherein the average particle size of said sinterable powder is comprised between 0.5 to 2.0 micrometers.